Sympathomimetics

Question 1

Mean Arterial Pressure Formula

Answer 1

CO x TPR

Question 2

Cardiac Output Formula

Answer 2

SV x HR

Question 3

Direct acting adrenergic agonists

Answer 3

Agonists for adrenergic receptors that can vary selectivity.

Question 4

Indirect acting adrenergic agonist

Answer 4

Act away from adrenergic receptors and generally alter release of catecholamines from adrenergic neurons.

Question 5

Mixed acting

Answer 5

Have direct and indirect agonistic effects.

Question 6

Baroreceptor Reflex

Answer 6

Respond to increases or decreases in blood pressure by adjusting sympathetic or parasympathetic output.

Question 7

Vasoconstriction

Answer 7

A1, A2 (minor),

Question 8

Vasodilation

Answer 8

B2

Question 9

Vascular Expression

Answer 9

Expressed in both arteries and veins, but primarily effects smaller arterioles and sphincters. Expression varies between vascular beds resulting in different responses to adrenergic stims.

Question 10

Vascular expression skin, nasal mucosa, or splanchnic.

Answer 10

A1

Question 11

Vascular Expression in Skeletal Muscle

Answer 11

B2 and A1

Question 12

Receptors corresponding to the Heart

Answer 12

B1(predominant) B2(important in HF)
Activation leads to increased SA node activity, increased AV node conduction velocity, increased myocardial contractility, leading to increased CO.
Alpha 1 receptors are also expressed and increase contractility in a minor way

Question 13

A1

Answer 13

Mydriasis, saliva increase, vasoconstriction(smooth and skeletal), GI relaxation, Bladder constriction, ejaculation

Question 14

A2

Answer 14

Vasoconstriction of mucosa, saliva, skin, splanchnic.

Question 15

B1

Answer 15

Renin secretion, increased fatty acid output, decreased GI motility.

Question 16

B2

Answer 16

Increased ciliary aqueous humor, increased respiratory secretions, relaxation of bronchial smooth muscle, bladder relaxation, increased glucose output

Question 17

Epinephrine

Answer 17

Agonist of both A and B receptors

Effects: Vasopressor, increased systolic pressure and decreased diastolic pressure, MAP unchanged(no baroreceptor reflex), increased HR, contractile force and CO, vasoconstriction, dilation of skeletal muscle vessels, decrease in TPR, bronchodilation, hyperglycemia, lipolysis.

Side Effects: Restlessness, headache, tremor, palpitations.
Cerebral hemorrhage(large or rapid doses), arrhythmia, angina(CAD).

Contraindications: Patients on Beta Blockers (unopposed activation of vascular A1 receptors resulting in severe HTN or cerebral hemorrhage).

Uses: Anaphylaxis, Bradyarrhythmias, asystole, mydriatic agent, glaucoma, co-administration with local anesthetic.

Question 18

Norepinephrine

Answer 18

Same as Epi, but does not activate beta 2

Effects: Increase in both systolic and diastolic pressure(increase in MAP). Baroreceptor reflex response. Decreased HR, Increased contractile force, CO unchanged. Vasoconstriction and increased TPR.

Side Effects: Greater elevation in BP than Epi, Severe HTN, Necrosis at injection site, Peripheral vascular insufficiency.

Uses: Raise BP. Cardiogenic shock. Septic shock. Spinal anesthesia.

Question 19

Dopamine

Answer 19

Low concentration is a D1 receptor agonist. High concentrations B1 and A1 agonist.

Low Dose: Vasodilation of renal, mesenteric, and coronary vasculature. Increases GFR and renal blood flow.

Intermediate Dose: B1 effects(HR up, Contractility up, Systolic up, Diastolic no effect)

High Dose: A1 effects(Vasoconstriction and TPR up).

Side Effects: Anxiety, headache, palpitations, angina pectoris, arrhythmias.

Uses: Decompensated Heart Failure, Cardiogenic Shock(NE preferred), Sepsis(NE preferred).

Question 20

Isoproterenol

Answer 20

Potent nonselective Beta agonist with low affinity for alpha receptors.

Decrease diastolic pressure, systolic pressure unchanged or increased, MAP decrease. Increased HR, contractile force and CO. Decreased TPR. Bronchodilation.

Palpitations, Tachycardia, Headache, Flushing, Ischemia or arrhythmia.

Emergency stimulation of heart rate in patients with Brady or HB. Generally replaced by Epi and Dopamine.

Question 21

Dobutamine

Answer 21

Non-selective B agonist

2 Isomers that are agonists of beta receptors

Minor BP effect, Increase contractility and CO. Minor effect of HR. Minimal effect on TPR.

Side Effects: Hypertensive patient’s may have an increase in HR or BP. A-Fib patients at risk of V-Tach due to increased AV conduction.

Uses: Cardiac Support CHF, After heart surgery, Acute MI.

Question 22

B2 Selective Agonists

Answer 22

Selective of B2, but not absolute. Developed for Pulmonary use. Delivered via inhalation to target particularly pulmonary tissue.

Bronchodilation. Reduced Airway Inflamation.

Side Effects: Tremor, Anxiety, Tachycardia, Rare arrhythmias or ischemia. Reduced adverse effects due to inhalational administration.

Question 23

Albuterol

Answer 23

Short Acting 3-6 hours. Bronchodilation in 15 mins. Used for Asthma, relief of bronchospasm.

Question 24

Salmeterol and Formoterol

Answer 24

Longer Acting(>12 hours) B2 agonist
Salmeterol slow onset
Formoterol quick onset
Used for COPD and Persistent Asthma.

Question 25

Mirabegron

Answer 25

B3 Selective Agonist
Bladder Relaxation
Side Effects: HTN, UTI, Headache.
Used for Urinary incontinence.

Question 26

Phenylephrine and Midodrine

Answer 26

A1 selective agonists
Increases systolic and diastolic pressure, decreases HR, vasoconstriction.
Used for hypotension, nasal decongestant, as a mydriatic agent.

Question 27

Ephedrine

Answer 27

Mixed Acting; Direct and Indirect, as it is an agonist for A and B receptors and enhances the release of NE from sympathetic neurons.

Effects: Increase BP, Increase HR and CO, Increases TPR, Increases resistance to urination, Bronchodilation, CNS stimulation.

Side Effects: HTN, Insomnia, adverse cardiovascular effects in people with underlying cardiovascular conditions.

Previously used to treat asthma. Dietary supplements were banned.

Question 28

Pseudoephedrine

Answer 28

Similar to ephedrine, but is a direct A1 agonist and has little effect of B2 activity.

Use: Decongestant.

Question 29

Cocaine

Answer 29

Indirect Sympathomimetic: Inhibits reuptake of NE and other neurotransmitters from synaptic cleft

Effects: Increased BP and HR

Side Effects: Arrhythmia, Ischemia, Myocarditis, Aortic Dissection, Cerebral Vasoconstriction.

Uses: Topical anesthetic of upper respiratory tract.

Question 30

Amphetamine

Answer 30

Indirect acting sympatho

CNS stimulant with peripheral sympathomimetic actions. Releases neurotransmitters from vesicles in sympathetic nerve terminals.

Effects: Increases systolic and diastolic pressures, Slows HR, Contraction of urinary sphincter, Unpredictable GI effects, Strong CNS effects.

Uses: Narcolepsy, ADHD.

*Dextroamphetamine: Greater CNS and less peripheral action.

Question 31

Methamphetamine

Answer 31

Indirect acting

Similar to amphetamine and ephedrine

More central stimulant effects with less peripheral sympathetic actions.

Question 32

Methylphenidate

Answer 32

Piperdine derivative, structurally similar to amphetamine.

Mild CNS stimulant. More prominent effects on mental than motor.

Both methamphetamine and methylphenidate are approved for narcolepsy and ADHD.